Table of Contents 3/30/2020 HBD MANUAL
Table of Contents Copyright 2019 Vestil Manufacturing Co. Page 6 of 21
• Pressure compensated flow control spool (2,000lb. & 4,000lb. rated load models only): Located beneath the
lowering valve, and regulates the fluid flow to the reservoir. This component allows the table to lower at the
constant rate independent of the weight of the dumper and contents. Several sizes are available.
• Hydraulic cylinders: 2,000 lb. and 4,000 lb. (capacity) models utilize displacement style cylinders. Each cylinder
includes a bleeder valve (located at top end) for removing air from the hydraulic system. 6,000 lb. capacity models
use double-acting cylinders.
• Velocity fuse: Safety device installed in the hose port of each cylinder. If a hose is punctured while the HBD is in
use, the velocity fuse closes automatically. The chute remains stationary until pressure is reapplied to the system.
• Hydraulic fluid: HO150 hydraulic fluid. To replenish the fluid, add anti-wear hydraulic fluid with a viscosity grade
of 150 SUS at 100°F (ISO 32 @ 40°C) like AW-32 or Dexron transmission fluid.
SEQUENCE OF OPERATION
A. Tilt the chute: Press the “UP” button. The motor turns and spins the gear pump. Oil flows out of the reservoir,
through the suction filter and into the pump.
• 2k & 4k rated load models: pump propels oil through the check valve to the lift cylinders.
• 6k rated load models: pressurized oil flows through the energized directional valve RT and into the blind end of
the lift cylinders; then oil is pressed out of the rod end and through a counterbalance valve 2CB. Counterbalance
valves prevent jerky movement as the chute reaches peak elevation (45° with horizontal).
• Releasing the UP button during operation will immediately halt all chute movement.
• An upper travel limit switch automatically turns off the motor when the chute reaches a preset 45° tilt angle.
B. Lower the chute: Press the “DOWN” button.
• 2k & 4k max. rated load models: lowering valve opens which bypasses the check valve and allows oil in the
cylinders to flow to the reservoir (through return hoses).
• 6k max. rated load models: The motor turns and the pump pushes the pressurized oil through the energized
directional valve LT and into the rod end of the lift cylinders. Oil flows from the blind ends of the cylinders and
through counterbalance valve 1CB, which regulates lowering speed and smoothness. A lower limit switch turns off
the motor when the chute is fully lowered.
• Releasing the DOWN button during operation causes all chute movement to stop. The chute will remain in the
same position until you press the DOWN button again and allow it to lower completely.
TROUBLESHOOTING MINOR ISSUES WITH THE HYDRAULIC SYSTEM
A. Chute slowly lowers on its own (without pressing the DOWN button): Remove, inspect, and clean the lowering
cartridge valve.
1. Lower the chute completely and unplug the AC cord.
2. If loaded, remove the container from the chute.
3. Remove the nut that fastens the solenoid coil to the valve stem, remove the coil, and then unscrew the valve
from the manifold.
4. Inspect the valve for blockage(s).
5. Inspect O-rings and back-up washers for cuts, tears, etc.
6. Submerge the valve in mineral spirits or kerosene and use a thin tool, such as a small screwdriver or a hex
wrench, to push the poppet in and out several times from the bottom end of the valve. The valve should
move freely, about 1/16” between the closed and open positions. If the poppet sticks, the valve stem might
be bent. Replace the poppet if it doesn’t free up after cleaning.
7. Remove mineral oil from the valve with compressed air.
8. Move the poppet in and out.
9. Inspect the bottom of the valve cavity in the manifold for foreign matter.
10. With the thin tool, press the middle of the flow control spool, which is located in the bottom of the cavity. It
should move down and up smoothly.
11. Reinstall the valve (in the manifold) and tighten the valve with 20 lb-ft of torque.
B. Chute lowers extremely slowly: Air in the cylinders might be the culprit. Air closes the velocity fuse, which
prevents oil from flowing out of the cylinders. Bleed the air from the system:
1. Lower the chute completely and unload the chute.
2. Locate the bleeder valve located at the top of each cylinder (it looks like a grease zirk). Bleed one (1) cylinder
at a time. Hold a rag over the valve and open it about 1/2 turn with a 3/8” or 5/16” wrench. Oil and air will
sputter from the valve. Jog the motor by pressing the UP button for just a second. If air continues to escape
from the bleeder valve, jog the motor several more times. Wait at least 5 seconds between successive jogs.
3. When air no longer is observed and only a clear stream of oil flows from the bleeder valve, close the valve.
4. Check the oil level in the reservoir. If the surface of the oil is lower than 1 to 1½ in. below the fill hole, add oil
until it is between 1 and 1½ inches of the fill hole.